Apparatus for high-temperature uses



UNITED STATES PATENT @FEWQE FRANK A. FAHRENWALD, OF CLEVELAND HEIGHTS,OHIO.

APPARATUS FOR HIGH-TEMPERATURE USES.

No Drawing.

.7 0 all whom it may concern:

Be it known that I, FRANK A. FAHREN WALD, a citizen of the UnitedStates, resid- This invention relates to alloys and has 7 for itsespecial object the provision of an inexpensive and mechanically strongcomposltion of matter which shall withstand repeated exposure to hightemperatures without material oxidation, disintegration or change ofshape. A great need exists for such an alloy in the manufacture of heattreating boxes; carbonizing boxes; lead pots; furnace parts; retorts forthe distillation of wood, coal oil and oil bearing shales; containersfor the production of calcium cyanamid; doors, chains, link and rabblearms for metallurgical furnaces; and many other metallurgical andchemical relations. Also such alloys in case they have the requisitehardness are of great value for cutting tools and tools for working hotmetal. All the foregoing uses are grouped under the expression Apparatusfor high temperature uses.

The essential desiderata of such appara tus are cheapness andavailability, coupled with reasonably long life. Containers, boxes, andsome other articles have been made from certain alloys of nickel andchromium, and serve very effectually the uses to which they are put buttheir expensiveness is absolutely prohibitive for most purposes, and thesame is true of most other compositions heretofore proposed for suchuses. The object of my invention is to secure a suflicieiiitly resistantalloy for most practical purposes with the use of inexpensiveingredients and without requirin expensive processes of manufacturing. 1y improved alloy may be either cast directly to shape or by suitableprecautions in composition can be machined as hereafter set forth.

-Although special substances may be added for special purposes ashereafter set forth my improved apparatus is ordinarily made from analloy containing essentially the following ingredients, (the firstcolumn showing substantially the preferred compo- Specification ofLetters Patent.

Patented Nov. 2, 1920 Application filed. August 25, 1919. Serial No.319,756.

sition'and the second column the variat1ons):

Iron 70% (%75%) Chromium 15% (10%20%) Cobalt 13.5% (10%-,20%) Manganesel.5% .2%1% Silicon .5% .2%3% Carbon .2%-3% The iron constitutes the baseof the alloy and is chosen for its cheapness, its amount decreasing withthe excellence of the composition, although preferably preponderant inall cases. The chromium affords resistance to oxidation at hightemperatures and increases the solubility of the minor constituents thusimproving the physical properties of the alloy. The cobalt is employedfor its toughening and hardening qualities. Cobalt in an amount of 10%or greater has a hardening effect superior to that produced by anyamount of nickel whatever. In quantities less than about 10% cobalt isnot appreciably superior to nickel in this regard, and sufiers thedrawback that its price is about three times that of nickel, while aboveabout 15% to 20% its hardening effect does not increase proportionallyto the increased price consequent upon its use. The manganese isemployed as a scavenger and to improve the casting qualities of thealloy. The silicon has a decided hardening effect and also the addedquality of shielding other ingredients against oxidation although in itslarger quantities it tends to produce brittleness which restricts itsuse;

The carbon tends to produce hardness, increases the resistance of thealloy to deformation at points below fusion and also i11- creases thefluidity of themolten alloy thus assisting in the casting. If the carbonand silicon are both restricted to .5% or less of the alloy, thearticles cast therefrom can be readily machined after annealing.

The addition to the alloy of from about 1% to about 8% of atungsten-like metal (by whichImean tungsten or molybdenum) greatlyincreases its resistance to distortion at high temperatures and soimproves it for many uses as for example in tools for working hot metal.

N 0 special precautions are required in the manufacture of the alloysince it can be made either in crucibles or by the electric furnacemethod although I prefer to employ the method described and claimed inmy application filed simultaneously herewith and denominated case E. Theonly precautions necessary are to restrict the carbon and silicon to thedesired limits and this is pe culiarly easy with my improved processalthough it can be accomplished in other ways. It is also necessary torestrict the sulfur and phosphorus to less than about .05 each which canbe effected by a proper selection of the ore coupled with the use ofsuitable slags and furnace linings as will be well understood by thoseskilled in the art of iron metallurgy. It will also be understood thatother ingredients can be added than those herein listed and generallythat many variations in composition are permitted within the scope ofthe claims hereto annexed.

Having thus described my invention what I claim is 1. Apparatus for hightemperature uses made from an alloy containing a preponderance of irontogether with from about 10 to per cent. of each of the metals cobaltand chromium, and at least about 2% of each of the substances carbon,silicon, and manganese.

2. Apparatus for high temperature uses made from an alloy containingfrom about 10 to about 20 per cent. of each of the metals cobalt andchromium, together with from about 2% to 3% of each of the substancescarbon and silicon, the bala c being mostly iron.

Apparatus for high temperature uses made from an alloy containing apreponderance of iron alloyed with ten to twenty per cent. of cobalt andsmall amounts of carbon, silicon, and manganese, the balance consist ingessentially of one or more metals from the chromium group.

4;. Apparatus for high temperature uses made from an alloy containing apreponderance of iron together with about ten to twenty per cent. ofeach of the metals cobalt and chromium, and about one to eight per cent.of a tungstendilre metal, and also small amounts of carbon and silicon.

Apparatus for high temperature uses made from an alloy containingsubstantially iron 70%, chromium 15%, cobalt 13% to 14% and fractionalpercentages of carbon, silicon, and manganese.

In testimony whereof, I hereunto aiiix my signature.

FRANK A. FAHRENWVALD.

